Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7990848 | Journal of Alloys and Compounds | 2018 | 27 Pages |
Abstract
The precipitation of α phase during ageing was investigated in the near-β titanium alloy Ti-17 considering either a fully βmetastable initial microstructure or a 35% αprimary + 65% βmetastable initial microstructure. In-situ electrical resistivity and high energy X-ray diffraction measurements revealed the influence of the initial microstructure, with different α morphologies (size and distribution of αprimary), as well as the heating rate on the precipitation sequences and kinetics following the decomposition of the β-metastable phase. Various amounts of metastable phases (Ïisothermal and αâ³isothermal) precipitate in temperature ranges that increase with the heating rate. From temperatures about 500â¯Â°C, the orthorhombic αâ³isothermal structure evolved towards the hexagonal close-packed α as temperature increased. SEM microstructure characterisations showed that slow heating rates promoted a fine and dense α precipitate distribution through the formation of Ïisothermal and/or αâ³isothermal, leading to higher hardness values. A higher heating rate restricted the precipitation of αâ³isothermal and shifted to the one of α at a higher temperature, leading to coarser precipitates. Furthermore, precipitation kinetics of αâ³isothermal/α were quicker considering an initial intragranular α precipitation as compared to α colonies.
Related Topics
Physical Sciences and Engineering
Materials Science
Metals and Alloys
Authors
Nicolas Maury, Benoît Denand, Moukrane Dehmas, Claude Archambeau-Mirguet, Jérôme Delfosse, Elisabeth Aeby-Gautier,